For safety reasons it is becoming an increasing practice to coat the walls of a mine with concrete, backed by reinforcing. The concrete is delivered to the mine in a fluid state then carried by conventional mining vehicles to the point of use and applied to the mine walls by compressed air. During transportation in the mine, insofar as known, no means is available to pick up the concrete ingredients and water at the well mouth, or other delivery point, then undertake mixing of the concrete during travel to the point of use. Instead the ingredients are separately hauled to a stationary mixing machine at the point of use.